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Dai H.,Yancheng Institute of Technology
Ceramics International | Year: 2017

A BaZrO3-based electrolyte with low Pr-doping concentration is proposed as electrolyte for proton-conducting solid oxide fuel cells (SOFCs). The new material BaZr0.75Y0.2Pr0.05O3-δ (BZYP5) shows a good chemical stability against CO2. In addition, the low doping concentration of Pr in BaZrO3 improves the sinterability of BaZrO3 and also allows its structure to remain stable even in the reducing atmosphere, which is critical for fuel cell applications. The cell with BZYP5 as electrolyte shows maximum power densities of 124, 70, and 43 mW cm−2 at 600, 550, and 500 °C, respectively, which are larger than that for the cell with conventional high Pr-doping BaZrO3 electrolyte reported previously. Electrochemical analysis indicates that the BZYP5 electrolyte shows a good ionic conductivity. These results suggest that the low Pr-doping strategy presented in this study promotes the densification for BaZrO3 and the good electrolyte conductivity of BaZrO3 is maintained which could be the reason for the improved cell performance, suggesting BZYP5 is a promising electrolyte for proton-conducting SOFCs. © 2017 Elsevier Ltd and Techna Group S.r.l.

Yao Z.,Jiangsu Key Laboratory of New Energy Generation and Power Conversion | Yao Z.,Yancheng Institute of Technology | Xiao L.,Jiangsu Key Laboratory of New Energy Generation and Power Conversion
IEEE Transactions on Power Electronics | Year: 2012

Renewable energy sources, such as solar energy and fuel cells, are desirable due to their pollution-free properties. In order to utilize the present infrastructure of the utility grid for power transmission and distribution, grid-connected inverters are required for distributed generation systems, which should have high reliability. However, a shoot-through problem, which is a major deterrent to the reliability of the inverters, exists in the conventional bridge-type voltage-source inverters. In order to solve the aforementioned problem, this paper proposes a two-switch dual-buck grid-connected inverter. The freewheeling current flows through the independent diodes instead of the body diodes of the switches, so reverse-recovery loss of the diodes can be reduced. Half of the power devices operate in high frequency; the others switch at grid period with zero-current switching. Moreover, uniploar modulation is used. The operating principle, design guidelines and example, and stability analysis are provided. The proposed inverter can be simplified to a current amplifier with hysteresis current control, so it is globally stable. Simulation and experimental results verify the theoretical analysis and satisfy IEEE Std. 929-2000. A comparison of a full-bridge inverter and the proposed inverter shows that the proposed inverter is more attractive in high-reliability applications. © 1986-2012 IEEE.

Wang Z.-G.,Yancheng Institute of Technology
Applied Mechanics and Materials | Year: 2013

Stepped distributed dynamic systems are widely used in the engineering fields, and the dynamic characteristics analysis of them is very important. In this paper, the axial vibration of a stepped bar consisting of two uniform sections is studied, in order to solve the dynamic equation, the differential transformation method is used, the governing differential equation and the boundary conditions of the bar become simple algebraic equations. Doing some simple algebraic operations for these equations, the closed form solution of natural frequency, mode shape and the dynamic response can be obtained. Comparison the results obtained by the differential transformation method and finite element method, excellent agreement is achieved, and the effects of the stiffness of spring is discussed in this paper. © (2013) Trans Tech Publications, Switzerland.

Luo J.,Yancheng Institute of Technology
Applied Mechanics and Materials | Year: 2012

Lithium niobate powders were prepared by mechanochemical treatments using Li 2CO 3 and Nb 2O 5 as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) were employed to evaluate the morphologies and structures of samples. The mechanism of LiNbO 3 formation of the ground mixture samples was discussed. The crystal structure of mixture was collapsed into a disordered structure, which increased with increasing grinding time. At the same time, the specific surface area increase and the bond energy reduction of the mixture occurred. Consequently, high energy ball milling enables increase of the internal energy, reduction of the activation energy, and improvement of the uniform mixing stage, which resulted in direct formation of singal phase LiNbO 3 at a low temperature (500°C). However, the temperature must reach 1200°C for the traditional method.

Luo J.,Yancheng Institute of Technology
Materials Letters | Year: 2012

Nanosized Nd-doped strontium ferrites, SrNd xFe 12-xO 19, with x = 0.0-0.5, were successfully prepared through a chemical coprecipitation process. The samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and vibrating sample magnetometer (VSM). Various parameters such as lattice constants (a and c) and crystallite size were calculated from the XRD data. The crystallite size was in the range of 28-39 nm. The specific saturation magnetization (M s) and the coercivity (H c) of strontium ferrites could be improved by substitutions of Nd 3+ ions on Fe 3+ ion basis sites. The M s revealed magnetic behavior with respect to Nd 3+ ion concentration, showing a decrease. The H c increased with increasing Nd 3+ ion concentration. © 2012 Elsevier B.V. All rights reserved.

Tian C.,Yancheng Institute of Technology | Zhang L.,Umeå University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

An inhomogeneous distribution of species density over physical space is a widely observed scenario in plankton systems. Understanding the mechanisms resulting in these spatial patterns is a central topic in plankton ecology. In this paper we explore the impact of time delay on spatiotemporal patterns in a prey-predator plankton system. We find that time delay can trigger the emergence of irregular spatial patterns via a Hopf bifurcation. Moreover, a phase transition from a regular spiral pattern to an irregular one was observed and the latter gradually replaced the former and persisted indefinitely. The characteristic length of the emergent spatial pattern is consistent with the scale of plankton patterns observed in field studies. © 2013 American Physical Society.

Luo J.,Yancheng Institute of Technology
Materials Research Bulletin | Year: 2013

NiCuZn-ferrite powders were synthesized by mechanochemical treatments using NiCO3×2Ni(OH)2×4H2O, CuO, ZnO and Fe2O3 as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) were employed to evaluate the morphologies and structures of samples. The results indicated that the mechanochemical treatment produced several structural and chemical effects on reactants of the powder mixtures, and single phase Ni0.45Cu 0.05Zn0.5Fe2O4 could be obtained after annealed at 700 C for 2 h. In comparison with the traditional firing method, the mechanochemical method benefited achieving the lower Ms and μi, which indicated that the sample had better magnetic properties. © 2013 Elsevier Ltd. All rights reserved.

Yao Z.,Nanjing University of Aeronautics and Astronautics | Xiao L.,Yancheng Institute of Technology
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents a control of single-phase grid-interactive inverters with nonlinear loads. The utility-connected inverter should operate at both stand-alone and grid-connected modes. However, the waveform qualities of the grid current in grid-connected mode and the output voltage in stand-alone mode are poor under the nonlinear critical load with the conventional control. The impact of the nonlinear load on the grid current is analyzed. The proposed control is illustrated in detail. By adding the load current into the filter inductor current loop, the influence of the nonlinear load on the grid current can be eliminated, and the waveform quality of the output voltage in stand-alone mode can be improved. The control method is simple and easy to be achieved. The grid-connected inverter is stable at both modes. The filter inductor is chosen. Simulation and experimental results from a 1-kW dual-buck full-bridge grid-interactive inverter with a diode rectifier load verify the theoretical analysis. © 2012 IEEE.

Ruiz-Baier R.,Ecole Polytechnique Federale de Lausanne | Tian C.,Yancheng Institute of Technology
Nonlinear Analysis: Real World Applications | Year: 2013

Cross-diffusion driven instabilities have gained a considerable attention in the field of population dynamics, mainly due to their ability to predict some important features in the study of the spatial distribution of species in ecological systems. This paper is concerned with some mathematical and numerical aspects of a particular reaction-diffusion system with cross-diffusion, modeling the effect of allelopathy on two plankton species. Based on a stability analysis and a series of numerical simulations performed with a finite volume scheme, we show that the cross-diffusion coefficient plays a important role on the pattern selection. © 2012 Published by Elsevier Ltd.

Tian C.,Yancheng Institute of Technology
Chaos | Year: 2012

Spatial patterns have received considerable attention in the physical, biological, and social sciences. Generally speaking, time delay is a prevailing phenomenon in aquatic environments, since the production of allelopathic substance by competitive species is not instantaneous, but mediated by some time lag required for maturity of species. A natural question is how delay affects the spatial patterns. Here, we consider a delayed plankton allelopathic system consisting of two competitive species and analytically investigate how the time delay affects the stability and spatial patterns. Based upon a stability analysis, we demonstrate that the delay can induce spatial patterns under some conditions. Moreover, by use of a series of numerical simulations performed with a finite difference scheme, we show that the delay plays an important role on pattern selection. © 2012 American Institute of Physics.

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